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authorDavid Henningsson <coding@diwic.se>2021-05-15 09:15:33 +0200
committerTakashi Iwai <tiwai@suse.de>2021-05-17 16:02:44 +0200
commit08fdced60ca08e34e316a3ab945636fcdfcbc973 (patch)
tree2ebf36f380c9bafbb78b43bb32de7118c8f4d529 /include/sound/rawmidi.h
parentbac59054544ebdb89f05c5b9598ca9cb2dea72ce (diff)
downloadlinux-08fdced60ca08e34e316a3ab945636fcdfcbc973.tar.bz2
ALSA: rawmidi: Add framing mode
This commit adds a new framing mode that frames all MIDI data into 32-byte frames with a timestamp. The main benefit is that we can get accurate timestamps even if userspace wakeup and processing is not immediate. Testing on a Celeron N3150 with this mode has a max jitter of 2.8 ms, compared to the in-kernel seq implementation which has a max jitter of 5 ms during idle and much worse when running scheduler stress tests in parallel. Signed-off-by: David Henningsson <coding@diwic.se> Reviewed-by: Jaroslav Kysela <perex@perex.cz> Link: https://lore.kernel.org/r/20210515071533.55332-1-coding@diwic.se Signed-off-by: Takashi Iwai <tiwai@suse.de>
Diffstat (limited to 'include/sound/rawmidi.h')
-rw-r--r--include/sound/rawmidi.h2
1 files changed, 2 insertions, 0 deletions
diff --git a/include/sound/rawmidi.h b/include/sound/rawmidi.h
index 334842daa904..989e1517332d 100644
--- a/include/sound/rawmidi.h
+++ b/include/sound/rawmidi.h
@@ -81,6 +81,8 @@ struct snd_rawmidi_substream {
bool opened; /* open flag */
bool append; /* append flag (merge more streams) */
bool active_sensing; /* send active sensing when close */
+ unsigned int framing; /* whether to frame input data */
+ unsigned int clock_type; /* clock source to use for input framing */
int use_count; /* use counter (for output) */
size_t bytes;
struct snd_rawmidi *rmidi;